From a clinical standpoint, Dr. Raper is interested in gastrointestinal surgical problems. In particular, his interests are in complex pancreatic, liver and biliary tract disease mesh well with the mission of the University of Pennsylvania Medical center as a quaternary referral center.

A second specific interest is metabolic surgery. The renaissance of interest in surgical procedures for the treatment of morbid obesity has created an opportunity for him to assist in the management of these complex patients. A second application is in the use of partial ileal bypass for the treatment of hypercholesterolemia. In both cases, surgery has proven capable of improving the metabolism of affected patients.